Q & A: Similarities and differences between COVID-19 and influenza in 2019

As the COVID-19 epidemic continues to evolve, people have compared it to the flu. Both viruses cause respiratory diseases, but they are very different and spread very differently. Clarifying these differences is important for taking targeted public health measures to fight both viruses.

What are the similarities between COVID-19 and influenza virus?

First, the COVID-19 virus and influenza virus cause similar disease symptoms. They all cause respiratory diseases, some patients are asymptomatic or mild, and some are severe or even die.

Second, both viruses are transmitted through contact, droplets, and contaminants. Therefore, the same public health measures can be taken, such as maintaining good hand hygiene and breathing etiquette . These measures are important for preventing infections.

What is the difference between COVID-19 virus and influenza virus?

A major difference between the two viruses is the speed of transmission. Compared with the COVID-19 virus, the influenza has a shorter median incubation period and a shorter interval between cases. The interval between COVID-19 cases is estimated to be 5-6 days, while the interval between influenza cases is 3 days. This means that the flu may spread faster than COVID-19.

In addition, the first 3-5 days of disease spread, or the spread that may occur before symptoms appear, are a major driver of influenza transmission. However, estimates of the COVID-19 virus and the influenza virus largely depend on the specific environment and time, so it is difficult to compare directly.

Children are an important source of transmission of influenza virus in the community. However, preliminary data indicate that children are less infected with COVID-19 virus than adults, and the clinical incidence is lower in the 0-19 age group. Further preliminary data from the Chinese Family Transmission Research Project indicate that children are infected by adults, not adults.

The symptoms of the diseases caused by the two viruses are similar, but it appears that the rate of severe illness is different. Children, pregnant women, the elderly, people with chronic underlying diseases, and immunosuppressed populations are at high risk of severe influenza infection. For COVID-19, we believe that aging and underlying diseases increase the risk of serious infections.

The mortality rate for COVID-19 appears to be higher than that of influenza, especially higher than seasonal influenza. It will take some time to determine the actual mortality of COVID-19. According to the data we have at present, the crude mortality rate is between 3% and 4%, and the infection mortality rate will be lower than this.

What medical interventions are available for the COVID-19 virus and influenza virus?

China is currently conducting clinical trials of multiple treatments. There are more than 20 vaccines in development worldwide. There is currently no licensed vaccine or treatment for COVID-19. There are currently many anti-influenza virus drugs and vaccines. Although the flu vaccine is not effective against the COVID-19 virus, we strongly recommend getting the flu vaccine every year to prevent infection with the flu virus.